Valve cover seems flat. I`ve flattened the screw hole dimples. I have NOT overtightened. IPD washers are in place. Gasket is new cork.

Leaks at rear acute angle of valve cover. I am about to commit sacrilege of a gasket sealer! I`d try IPD alloy cover if I wasn`t so cheap. My cover must be warped somehow, right?

Any suggestions before I break out the RTV? Techniques for checking flatness/adjusting of gasket surface?

Many thanks!

Used the IPD nitrile gasket. No "gorilla snot" on either side. I`m too klutzy and got that stuff everywhere! It seemed to want to dry before I could get it evenly spread. No leaks so far.

Great ideas all. I ordered the nitrile gasket (IPD) just to try. I`ll probably go with "gorilla" on cylinder head side alone. Great suggestion about checking the valve cover flatness against the cylinder head Danny. Will definitely do that.

Although it's difficult to determine that the valve cover is flat (as in one plane) you can check each edge with a good straightedge, and then placing the cover on the cleaned head (without gasket) you can rock it to find the high spot(s). Just keep tapping with your hammer (judiciously) until it's flat. I vote for the gasket on the cover for the aforementioned reason of cork in the gallery. A flat cover and the metal tabs around the inside of the cover holding a good cork gasket in place are usually sufficient.

I have an alloy cover on one motor and damned if either the gasket is a wee short (end to end) or more likely the cover is "long" (how's that possible if I got it from IPD?) and in that case I glued and 'stretched' the gasket in place (on the cover) to get good surface bearing - cover to gasket to head.

Don't use RTV.
I got the best reults using 3M weatherstrip adhesive ("gorilla snot").
Clean the head surface and glue the gasket to the head; no sealer on the cover.

That sounds backwards to me. I always glued the gasket to the cover, with old style Permatex, and often was able to reuse it a few times as it would come away cleanly from the head if it hadn't been on there too long. Also, when it comes time for the next replacement, its a lot easier to clean the cover of old gasket and glue residue, than it is to do the same to the mating surface of the head. All the particles try to fall down the pushrod holes as you are scraping---with it glued to the cover, you can take it somewhere else and nothing goes down inside the engine.

I once had an ipd aluminum valve cover, the one everyone wants with the cast in logo, and it was nothing but trouble---couldn't get it to stop leaking. Replaced it with a stamped tin one, and a new gasket, and it was fine ever after.

I have one of those pricey valve covers. It came with my car and leaked at the rear. A close inspection, a little digging around, and asking on BB told me that the cover itself is not quite "right." That is, the cover is not quite the right shape. I bought one of those neoprene gasket seals from IPD and used the gorillas snot to glue it to a very clean head surface and did not glue it to the cover. The extra 1/4" of the seal keeps the oil from pooling up and running over the seal and stops that obnoxious chronic oil mess down the back of the motor.

I've have consistent issues with leaking cork gaskets on a 1972 B20B, a 1971 B20E, and a 1967 B18D with both cast and stamped valve covers.

In my experience, the neoprene seal is the only thing that has ever worked reliably. I'd say that it's well worth the $10-15.00 in seeped oil alone.

Could be a crappy cork gasket. A couple years ago I replaced mine, don't remember where the new one came from. When I replaced it I noticed that the new one was thinner and the surface was a little rougher than the old one, but figured it'd be OK. Basically it disintegrated in the middle of Kansas on a long road-trip, leaking oil all over. Scared up a replacement from a brickboard member, which was thicker and smoother, like the original, and after some time spent at a carwash all was well. All of which is to say it could be the gasket. I've since bought a silicone gasket from IPD that I keep in the car for if/when the current cork gives out, but no sign of that.